Launderable retroreflective applique with metal-azo dye

ABSTRACT

Retroreflective appliques comprising a monolayer of retroreflective elements partially embedded in and protruding from the front surface of a binder layer and an optional layer of adhesive on the rear surface of the binder layer, wherein the binder layer, the adhesive layer, or both contain a metal-azo dye to camouflage the color of any exposed portions of said binder layer. Appliques comprising micropheres with aluminum reflectors as retroreflective elements and a black metal-azo dye in the binder layer will exhibit a pleasing silver appearance even after portions of the binder layer have been visibly exposed due to degradation of the aluminum reflectors, typically as a result of subjecting the applique to harsh laundering conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 07/954,331,filed Sep. 30, 1992, now allowed as U.S. Pat. No. 5,338,595, which is acontinuation-in-part of application Ser. No. 07/697,653, filed May 8,1991, now abandoned.

FIELD OF INVENTION

The present invention relates to novel retroreflective appliques andarticles made with such appliques.

BACKGROUND

In order to improve safety of pedestrians, joggers, workers on roadways,etc., retroreflective markings have been attached to clothing. In onecommon embodiment, retroreflective appliques comprising a monolayer ofretroreflective elements, e.g., transparent microspheres withhemispheric reflectors, partially embedded in a layer of bindermaterial, with adhesive backings are bonded to articles of clothing.

A problem with such appliques is that when the garment to which they areapplied is laundered, a number of the retroreflective elements may bedislodged, the elements may be degraded, or the binder material may tendto discolor, e.g., turn somewhat yellow or green, resulting inundesirable discoloration of the applique. Typically, the binder layersin such appliques contain pigments such as carbon black, titaniumdioxide, or flakes of metallic aluminum. In addition to imparting adesired initial coloration to the applique, these pigments serve tostabilize the color of the applique, masking discoloration of theapplique when it is laundered. The pigments are sometimes referred to asa camouflage or camouflaging agent because they hide the discolorationof the binder material. In some cases, pigments provide other desiredeffects as well, e.g., antimony oxide imparts flame retardantcharacteristics to binder layers in which it is incorporated.

The loadings of pigments which are necessary to achieve the desireddegree of coloration stability and camouflage, e.g., often 1 weightpercent or more, may tend to reduce the flexibility of the binder layer,causing the applique to be less flexible and increasing itssusceptibility to loss of retroreflective elements when flexed. In someinstances, the pigment may alter the characteristics of the bindermaterial so as to interfere with adhesion of the retroreflectiveelements by the binder layer. During fabrication of the applique, thepigments may settle to the retroreflective element/binder materialinterface, further interfering with desired adhesion. In some instances,the pigment itself is degraded, e.g., aluminum flakes tend to oxidize,particularly when laundered under high pH conditions, so as to becometranslucent, reducing the desired camouflaging effect.

As a result, some desired combinations of coloration and durability arenot obtained.

The problem is particularly troublesome when the clothing is subjectedto industrial laundering, where the conditions of laundering are oftenmore severe than conventional home laundering. For instance, in anindustrial laundry, the laundering conditions may include washtemperatures of 40° to 90° C. (105° to 190° F.) and pH of 10 to 12.5,whereas in contrast, typical conditions for home laundering may includetemperatures of 4° to 60° C. (40° to 140° F.) and pH of less than 11.Also, home laundering equipment typically subjects the articles beingcleaned to less rigorous handling and stress than does industriallaundry equipment.

SUMMARY OF INVENTION

The present invention provides novel retroreflective appliques which canbe applied to substrates such as fabrics and garments to impartretroreflective properties thereto. The appliques of the inventionprovide unexpected durability, particularly in terms of their ability tomaintain a uniform appearance (color) when subjected to harsh launderingconditions. Applied to fabric substrates, appliques of the inventionexhibit surprising resistance to degradation when the article islaundered and retain a surprising degree of their initial coloration,e.g., the initial silver appearance of an aluminum vapor coat, andretroreflective properties.

In brief summary, retroreflective appliques of the invention comprise amonolayer of retroreflective elements partially embedded in andprotruding from the front surface of a binder layer and an optionallayer of adhesive, preferably hot melt type, on the rear surface of thebinder layer. The adhesive layer is optionally covered with a removablerelease liner. In some embodiments, the applique is bonded to asubstrate, e.g., a piece of fabric or article of clothing, with theadhesive, and in other embodiments the binder layer serves to bothsecure the retroreflective elements and to bond the applique to adesired substrate. If desired, the applique can be sewn onto asubstrate. In an important distinction from previously knownretroreflective appliques, the binder layers and/or the adhesive layersof appliques of the invention comprise metal-azo dyes which impartdesired coloration and camouflage properties thereto by camouflaging thecolor of any visibly exposed portions of the binder layer. Portions ofthe binder layer can become visibly exposed as a result of degradationof the reflective layers of the retroreflective elements. Suchdegradation can be caused by harsh laundering conditions.

Retroreflective appliques of the invention have been found to exhibitsurprising retention of initial coloration and retroreflectivebrightness, particularly when subjected to industrial launderingconditions. As a result, articles to which appliques of the inventionhave been applied may be laundered many more times than previouslypossible while still retaining their desired initial coloration andretroreflective character.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be further explained with reference to the drawing,wherein:

FIG. 1 is cross-sectional illustration of a portion of an illustrativeembodiment of a retroreflective applique of the invention; and

FIG. 2 is cross-sectional illustration of a portion of anotherillustrative embodiment of a retroreflective applique of the inventionbonded to a substrate.

These figures, which are idealized, are not to scale and are intended tobe merely illustrative and non-limiting.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Reference is made to FIG. 1 wherein is shown an illustrative embodimentof retroreflective applique 10 of the invention. Applique 10 comprises amonolayer of retroreflective elements 12 partially embedded in andprotruding from front surface 14 of binder layer 16. Disposed on rearsurface 18 of binder layer 16 is optional adhesive layer 20. Applique 10is shown with optional release liner 22 which covers the exposed surfaceof adhesive layer 20. To apply applique 10 to a substrate such as afabric (not shown), release liner 22 is first removed. Applique 10 isalso shown on optional temporary carrier 8 comprising paper sheet 4 andpolymer lining 6.

FIG. 2 shows retroreflective applique 10 on substrate 30, e.g., anarticle of clothing such as a jacket or vest.

In brief summary, a typical method of making appliques of the inventioncomprises arranging retroreflective elements in desired monolayerarrangement on a temporary carrier with the rear portions of theretroreflective elements presented away from the carrier, forming abinder layer over the rear portions of the retroreflective elements, andapplying an optional adhesive layer on the back side of the binderlayer.

The most typical form of retroreflective elements 12 will be sphericalmicrospheres 24 having reflectors 26 thereon as shown in FIG. 1. Asknown to those skilled in the art, one method for assembling a monolayerof such retroreflective elements is to cascade microspheres ontotemporary carrier 8 which secures microspheres 24 in desired arrangementtemporarily. For instance, microspheres 24 can be partially embedded inheat softenable polymer layer 6 on paper sheet 4. Some examples ofuseful polymer coatings include polyvinyl chloride, polysulfones,polyalkylenes such as polyethylene, polypropylene, and polybutylene,polyesters such as polyethylene terephthalate, and the like. Uponcooling, polymer layer 6 retains microspheres 24 in desired arrangement.Depending in part upon the characteristics of carrier 8 and elements 12,it may be desired to condition carrier 8 and/or elements 12 to achievedesired release properties. For instance, selected release agents oradhesion promoters may be used.

Microspheres 24 are typically preferably packed as closely as possible,ideally in their closest hexagonal arrangement, to achieve greaterretroreflective brightness and may be so arranged by any convenienttransfer process, such as printing, screening, cascading, or with a hotcan roll.

The most typical kind of retroreflective elements are transparentmicrospheres having reflectors on the rear surfaces thereof as shown inFIG. 1. Such retroreflective elements typically provide satisfactorylevels of retroreflective brightness over a wide range of incidenceangles, i.e., the angles at which the light strikes the sheeting, aproperty sometimes referred to as "angularity".

If transparent microspheres are used, the microspheres are preferablysubstantially spherical in shape in order to provide the most uniformand efficient retroreflection. Furthermore, the microspheres arepreferably substantially transparent so as to minimize the amount oflight absorbed by the microspheres and thereby optimize the amount oflight which is retroreflected by sheetings of the invention. Themicrospheres are typically substantially colorless, but, may be coloredto produce special effects if desired.

Microspheres used herein may be made from glass or synthetic resinhaving the optical properties and physical characteristics taughtherein. Glass microspheres are typically preferred because theytypically cost less, are harder, and exhibit superior durability tomicrospheres made of synthetic resins.

Microspheres used in the present invention will typically have anaverage diameter of between about 30 and about 200 microns. Microsphereswhich are smaller than this range may tend to provide lower levels ofretroreflection because of diffraction effects, whereas microsphereslarger than this range may tend to impart undesirably rough texture tothe transfer or undesirably reduce the flexibility thereof. Microspheresused in the present invention will typically have a refractive index ofbetween about 1.7 and about 2.0, the range typically considered to beuseful in microsphere-based retroreflective products where, as here, thefront surfaces of the microspheres are exposed or air-incident.

As mentioned above, microsphere-based retroreflective elements ofretroreflective transfers of the invention have reflectors on the rearsurfaces thereof. Typically, such reflectors are applied to the rearsurfaces of the microspheres after the microspheres have been partiallyembedded in the carrier, thereby facilitating the arrangement of themicrospheres in substantially uniform direction for retroreflection.Furthermore, as is known, the size of reflectors, i.e., how much of thesurface of the microspheres which is covered, may be controlled in partby controlling the depth into the carrier to which the microspheres areembedded prior to application of the reflectors thereto.

Among the variety of materials which may be used as reflectors arevacuum-deposited or vapor-coated metal coatings, such as aluminum orsilver; chemically-deposited metal coatings, such as silver;metal-coated plastic films; metal flakes; such as aluminum or silver;and dielectric coatings. Aluminum or silver coatings are typicallypreferred, because they tend to provide the highest retroreflectivebrightness. The reflective color of silver coatings is typicallypreferred to that of aluminum coatings, but an aluminum vapor coat isnormally more preferred, because silver reflective coatings typicallysuffer more severe degradation in outdoor exposure than do aluminumcoatings. U.S. Pat. No. 3,700,305 (Bingham) discloses dielectric mirrorsor coatings that may be used as reflectors in retroreflective articlesof the invention.

An advantage of dielectric reflectors is that appliques made withmicrospheres having such reflectors may be easily made in a variety ofbright colors. Such reflectors are typically subject to degradationunder laundering conditions, particularly industrial launderingconditions, and are accordingly used on articles destined only for homelaundering. Aluminum and silver reflectors are generally less expensivethan dielectric reflectors and typically exhibit substantially greaterdurability under industrial laundering conditions, although partiallydegraded (oxidized) aluminum reflectors typically impart a dull graycolor to the applique rather than imparting the initial silver color ofthe aluminum reflectors.

Following arrangement of retroreflective elements 12, a bindercomposition that forms binder layer 16 is applied thereover. Binderlayer 16 is typically between about 50 and about 250 microns (2 and 10mils) thick over the embedded portion of retroreflective elements 12,with thicknesses of between about 75 and about 100 microns (3 and 4mils) typically being preferred. It will be understood that binderlayers having thicknesses outside these ranges may be used. However, ifbinder layer 16 is too thin, it will not provide sufficient support toretroreflective elements 12 which will be readily dislodged, whereasincreasing the thickness of binder layer 16 leads to increased cost forapplique 10 as greater amounts of the binder material are required.Also, the flexibility of applique 10 typically tends to decrease as thethickness is increased.

The binder composition comprises binder material, e.g., e-beam curedpolymeric materials; one or two component urethanes; nitrile rubber;acrylics; polyesters; epoxy; thermoplastic elastomers; vinyls such aspolyvinyl chloride, polyvinylacetate, and their copolymers; etc., andone or more metal-azo dyes.

The binder composition may further comprise one or more optionalcomponents, including crosslinkers, coupling agents, and stabilizers(e.g., thermal stabilizers and antioxidants such as hindered phenols andlight stabilizers such as hindered amines or ultraviolet stabilizers),flame retardants, and flow modifiers (e.g., surfactants such asfluoropolymers or silicones).

In one preferred embodiment, the binder composition is an e-beam curedpolymeric material as appliques made with certain e-beam cured polymericmaterials typically provide superior performance as compared to thosemade with other binder materials. One useful example of such desirablee-beam curable binder materials is the HYPALON™ series of polymers, aseries of chlorosulphonated polyethylenes from E. I. du Pont de Nemours& Company ("du Pont"). Such materials are highly flexible, and have beenfound to be resistant to degradation by exposure to ozone, oxygen,weathering, oil, and many chemicals as well as harsh launderingconditions. Illustrative examples of other desirable e-beam curablebinder materials that can be used include ethylene copolymers comprisingat least about 70% by weight of polyethylene such as ethylene/vinylacetate, ethylene/acrylate, and ethylene/acrylic acid, andpoly(ethylene-co-propylene-co-diene) ("EPDM") polymers.

Another preferred binder material is crosslinked polyester. Illustrativeexamples of such materials include the VITEL™ Copolyester series fromGoodyear Tire & Rubber Co. and BOSTIK™ Polyester Resin from Emhart Corp.

The binder composition contains between about 0.01 and about 2.0 weightpercent, preferably between about 0.1 and about 0.5 weight percent, ofmetal-azo dye. The metal-azo dye component may be a single metal-azo dyeor a combination of more than one metal-azo dye of selected color.Metal-azo dye is preferred because it provides the most effectivecamouflage of the color of any exposed portions of the binder material.It is understood that portions of the binder material can become exposedupon degradation of the reflectors. Since binder materials often have acolor which is not aesthetically pleasing, it is typically desirable tocamouflage the color of the binder material. Since appliques of theinvention are intended to be secured to launderable substrates, it iscritically important that they comprise dyes which are resistant todegradation or leaching out during laundering. Appliques comprisingmicrospheres with aluminum reflectors as retroreflective elements and ablack metal-azo dye in the binder layer in accordance with the inventionwill exhibit a pleasing silver appearance even after portions of thebinder layer have been visibly exposed due to degradation of thealuminum reflectors, typically as a result of subjecting the applique toharsh laundering conditions.

The metal-azo dyes used herein are soluble in organic solvents such asmethyl ethyl ketone, toluene, xylene, ethyl acetate, cyclohexanone,etc.; thus providing a potential processing advantage when incorporatingthem into binder compositions in accordance with the invention. Indistinction, pigments, the conventionally used colorant inretroreflective appliques, are insoluble in such solvents.

Metal-azo dyes for use in appliques of the invention are believed to beresistant to degradation or leaching out during laundering for a varietyof reasons. For instance, ionic dyes with relatively high degrees ofhydrophilicity tend to be subject to undue degradation and/or leachingduring laundering. Dyes which are used in thermal dye transfer processeswherein they must undergo diffusion and/or sublimation under roomtemperature or moderately elevated temperatures would typically beexpected to not be sufficiently resistant to leaching out of the binderlayer during laundering. In general, metal-azo dyes having molecularweights above about 300 will be suitable for use herein. Dyes havingpolar functionalities and those with amino- and hydroxyl- derivativefunctional groups generally exhibit improved laundering performance ascompared to otherwise similar dyes lacking those or similar groups. Dyeswith functional groups that would anchor to the binder material wouldexhibit greater resistance to diffusion out of the binder layer.

Metal-azo dyes, which are based on heavy metal complexes, exhibit greatstability in binder layers of launderable appliques and thus arepreferred. Illustrative examples of metal-azo dyes which are usefulherein include: chromium-azo dyes, such as ZAPON™ X50 or X51 (black),ZAPON™ Yellow 156 and 157, ZAPON™ Red 335 and 471, ZAPON™ Violet 506,ORASOL™ CN and RL (black) and ORASOL™ Red B and Red G from Ciba-Geigy.

The following dyes are also believed to be resistant to degradation orleaching out during laundering, but are not believed to be as effectiveas metal-azo dyes: anthroquinone dyes, e.g., PEROX™ Yellow GS, PEROX™Magenta 36, PEROX™ Red LB, and MORTON™ Violet 14 from Morton Thiokol,ATLASOL™ Cerise NA from Atlantic Company, WAXOLINE™ Blue APFW from ICI,and NITROFAST™ Blue 2B from Sandoz; aminoketone dyes, e.g., HOSTASOL™Yellow 3G from Hoechst Celanese; quinophthalone dyes, e.g., MACROLEX™Yellow G from Bayer and THERMOPLAST™ Yellow 154 from BASF; pyrazolonedyes, e.g., MACROLEX™ Yellow 3G from Bayer and THERMOPLAST™ Yellow 104from BASF; and phthalocyanine dyes, e.g., ZAPON™ Blue 806 and 807 andORASOL™ Blue GN and BLN from BASF.

As mentioned above, the binder composition may further comprise one ormore crosslinkers. Selection of crosslinker and its amount will bedependent in part upon the elastomer which is used.

Illustrative examples of crosslinkers which may be used with e-beamcurable elastomers include multifunctional monomers and oligomers suchas trimethylolpropane trimethacrylate, pentaerythritol triacrylate, andtriallyl-1,3,5-triazine-2,4,6(1H,3H,5H)trione. Illustrative examples ofother useful crosslinkers include 1,6-hexanediol diacrylate,tetraethylene glycol diacrylate, neopentylglycol diacrylate,tripropylene glycol diacrylate, trimethylolpropane ethoxy triacrylate,tris(2-hydroxethyl) isocyanurate triacrylate, dipentaerythritolpentaacrylate, urethane acrylate oligomers (e.g., CN970 series fromSartomer Co. and EBERCRYL™ from Radcure Specialties, Inc.), epoxyacrylate oligomers, and acrylic oligomers. Crosslinkers may be usedalone or in combination of one or more. Typically, the binder layer willcontain up to about 10 weight percent, and preferably between about 0.5and about 2 weight percent, of such crosslinker. If too much crosslinkeris used, the resultant binder layer may tend to be insufficientlyflexible. Also, because many crosslinkers tend to be susceptible todegradation due to water and high pH, binder layers made with excessiveamounts may tend to suffer impaired launderability. If too littlecrosslinker is used, the resultant binder layer may not be curedsufficiently and thus be subject to degradation, e.g., swelling andretroreflective element loss, under laundering conditions, or requirehigh e-beam dosage to achieve sufficient cure.

Typically, binder layer 16 will comprise one or more coupling agents,e.g., silane coupling agent, to promote adhesion of binder layer 16 toretroreflective elements 12. Selection of a coupling agent will be basedin part upon the particular elastomer, crosslinker (if any), andretroreflective elements which are used. Illustrative examples ofcoupling agents include vinyltrimethoxysilane, vinyltriethoxysilane,gamma-methacryloxypropyl-tris-(2-methoxyethoxy)silane,gamma-methacryloxypropyltrimethoxysilane,beta-(3,4-epoxycyclohexy)ethyltrimethoxysilane,gamma-glycidoxypropyltrimethoxysilane,gamma-mercaptopropyltriethoxysilane,gamma-mercaptopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane,and N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane. These may beused singly or in combination. It will be understood that selection ofcoupling agent(s), if used, will be dependent in part upon the bindermaterial and retroreflective elements used. To minimize fading ofaluminum reflector layers, it is typically preferred thatamino-containing silane coupling agents be avoided. If the bindermaterial is a two part urethane or a isocyanate cured polyester, epoxyor methacryloxy functional silane coupling agents are preferably usedand silane coupling agents containing active hydrogen moieties arepreferably avoided. Gamma-glycidoxypropyltrimethoxysilane,gamma-mercaptopropyltrimethoxysilane, andgamma-methacryloxypropyltrimethoxysilane have been found to exhibit thebest performance with chlorosulphonated polyethylenes among those listedand are preferred.

The coupling agent may be applied, e.g., by spraying or coating, to thesurfaces of the retroreflective elements or to the binder layer prior toits application to the elements or may be incorporated directly into thebinder composition. Application to the elements provides the advantageof using lesser quantities of coupling agent, which in some instances isrelatively expensive, whereas incorporation into the binder compositionprovides the advantage of eliminating a separate application processduring fabrication of the retroreflective applique.

Typically, binder layer 16 will contain up to about 10 weight percent,and preferably between about 0.1 and about 7 weight percent, of couplingagent. If too little coupling agent is used, the resultant applique may,depending upon the characteristics of the elastomer, tend to sufferundesirable loss of retroreflective elements. If too much coupling agentis used, it may in some instances impair the physical properties of thebinder layer, e.g., mercapto-based agents may cause the binder to swell.Also, the coupling agents are typically relatively expensive as comparedto the other components of the appliques.

In another embodiment of the invention, the metal-azo dye can beprovided in adhesive layer 20 of applique 10. In this embodiment,metal-azo dye can be provided in binder layer 16 or not included inbinder layer 16 at all. The metal-azo dye in adhesive layer 20 serves tocamouflage the color of any visibly exposed portions of binder layer 16,i.e., portions of binder layer 16 that have been visibly exposed due todegradation of reflectors 26 of applique 10.

It is believed that retroreflective appliques of the inventioncomprising a metal-azo dye in the binder layer, adhesive layer, or bothexhibit suprising retention of initial coloration and retroreflectivebrightness irrespective of what type of binder or adhesive material isused.

EXAMPLES

The invention will be further explained by the following illustrativeexamples which are intended to be non-limiting. Unless otherwiseindicated, all amounts are expressed in parts by weight.

Unless otherwise indicated, the following test methods were used.

Retroreflective Brightness

Retroreflective brightness was measured using a retroluminometer asdescribed in U.S. defensive publication T987,003 at divergence angles ofabout 0.2° and entrances angles of about -4°.

Laundering

Launderability of appliques was evaluated by washing a piece of fabricto which the subject applique had been applied for the indicated numberof cycles in a Milnor System 7 Washing Machine Model 30015M4G fromPellerin Minor Corp. using program no. 5 for medium soiled, coloredfabric with the indicated detergent. Each cycle is about 40 minutes inlength. The washer was loaded with about 5.5 to 6.8 kilograms (12 to 15pounds) (dry) of laundry and used about 68 liters (18 gallons) of waterat the indicated temperature.

The cleaning agent used was 30 grams of FACTOR™ detergent, a detergentfrom Fabrilife Chemicals, Inc. containing tetrasodium pyrophosphate,nonylphenoxypoly(ethyleneoxy)ethanol, sodium carbonate, and silica. Insome cases, the detergent further included 60 grams of ULTRASIL™, a pHbuilder from Pennwalt Corp. believed to contain 40 weight percent NaOHand 60 weight percent sodium metasilicates.

CIE Color Shift

The CIE Color shift, referred to herein as Delta E, was determined usingthe CIE tristimulus color coordinates, i.e., L, a, and b, as measuredwith a Minolta Chroma Meter C-121. Delta E was calculated as the squareroot of the sum of the squares of the changes on each of the coordinateaxes in accordance with ASTM D2244-79.

EXAMPLE 1

Glass microspheres having an average diameter of about 40 to 90 micronswere partially embedded in a temporary carrier sheet and aluminumspecular reflective layers applied to the exposed portions of themicrospheres to yield retroreflective elements.

A binder composition comprising:

    ______________________________________                                        Amount    Component                                                           ______________________________________                                        35        Binder Material - 40 weight percent solids                                    solution in methyl ethyl ketone of polyol                                     based on polytetramethylene oxide having                                      hydroxy equivalent weight of 3000;                                  2.23      Binder Material - 40 weight percent solids                                    solution in methyl ethyl ketone of                                            DESMODUR ™ N-100, an aliphatic                                             polyisocyanate adduct based on                                                hexamethylene diisocyanate from Mobay                                         Corp.;                                                              0.12      Catalyst - 10 weight percent solution in                                      methyl isobutyl ketone of dibutyl tin                                         dilaurate; and                                                      1.49      Dye - 10 weight percent solution in methyl                                    isobutyl ketone of ZAPON ™ X-51, a black                                   chromium-azo dye;                                                   ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about250 microns (10 mils). The applique was then wet laminated to aPRIMALUX™ fabric (an 80/20 blend of polyester and combed cotton, weight3 ounces/yard²) from Springs Industries, Inc., and the laminate dried at66° C. (150° F.) for 5 minutes then at 82° C. (180° F.) for 10 minutes.The temporary carrier was then stripped from the front of the appliqueto reveal the silver colored retroreflective surface.

EXAMPLE 2 AND COMPARATIVE EXAMPLE A

In Comparative Example A, an array of retroreflective elements on atemporary carrier was prepared as in Example 1.

A binder composition comprising:

    ______________________________________                                        Amount   Component                                                            ______________________________________                                        82.8     Binder Material - 33 weight percent                                           solution in methyl ethyl ketone of                                            HYPALON ™ 20;                                                     1.8      Coupling Agent - A-189, a gamma-mercapto-                                     propyltrimethoxysilane from Union                                             Carbide Corp.;                                                       0.4      Crosslinker - trimethylolpropane                                              trimethacrylate having molecular weight                                       of 338 from Aldrich Chemical Co.; and                                0.2      Pigment - 55 weight percent solution in                                       methyl ethyl ketone of MICROLITH ™ Black                                   C-T, a carbon black pigment predispersed                                      in modified rosin ester resin from                                            Ciba-Geigy Corp.,                                                    ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about300 microns (12 mils) and dried at 66° C. (150° F.) for 30 minutes. Thedried film was then e-beam irradiated to an exposure of 3 Mrads at 200kilovolts to yield the binder layer. An Mrad is a megarad where a tad or"radiation absorbed dose" is equal to 100 ergs/gram.

An adhesive composition comprising 100 parts of a 40 weight percentsolids solution in methyl ethyl ketone of a polyol having a hydroxyequivalent weight of 3000 and 8.8 parts of MONDUR™ CB75, a 75 weightpercent solids solution in ethyl acetate of an aromatic polyisocyanateadduct based on toluene diisocyanate, from Mobay Corp. was coated overthe binder layer to a wet thickness of about 200 microns (8 mils) as anadhesive layer.

The applique was then wet laminated to a fabric as in Example 1. Thetemporary carrier was then stripped from the front of the applique toreveal the silver colored retroreflective surface.

In Example 2, a monolayer of retroreflective elements was prepared as inExample 1.

A binder composition comprising:

    ______________________________________                                        Amount    Component                                                           ______________________________________                                        100       Binder Material and Dye - solution in                                         methyl ethyl ketone of 35 weight percent                                      HYPALON ™ 20 and 0.046 weight percent                                      ZAPON ™ X-50;                                                    2.1       Coupling Agent - A-189; and                                         0.2       Crosslinker - trimethylolpropane                                              trimethacrylate having weight average                                         molecular weight of 338 from Aldrich                                          Chemical Co.;                                                       ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about300 microns (12 mils) and dried at 66° C. (150° F.) for 30 minutes. Thedried film was then e-beam irradiated to an exposure of 3 Mrads at 200kilovolts to yield the binder layer.

An adhesive composition like that in Comparative Example A was thenapplied over the binder layer. The applique was then wet laminated to apolyester fabric (S-551-060, 3.11 ounce/yd² from Milliken & Co.). Thetemporary carrier was then stripped from the front of the applique toreveal the silver colored retroreflective surface.

The appliques were then evaluated by washing for the indicated number ofcycles at a water temperature of about 77° C. (170° F.) using FACTOR™and ULTRASIL™ cleansers. The initial retroreflective brightness of theapplique in Example 2 was about 597 candela per square meter per lux andthat of the applique in Comparative Example A was about 603 candela persquare meter per lux. The retroreflective brightness retention resultsobtained are shown in Table I.

                  TABLE I                                                         ______________________________________                                        Brightness.sup.2                                                              Cycles.sup.1   Ex. 2  Comp. Ex. A                                             ______________________________________                                                       100    100                                                      5             70     70                                                      10             40     43                                                      15             24     10                                                      20             15     TD.sup.3                                                ______________________________________                                         .sup.1 Number of wash cycles completed.                                       .sup.2 Percentage of its initial brightness that indicated sample retaine     after indicated number of wash cycles.                                        .sup.3 Test Discontinued because brightness had declined so severely.    

After 15 laundering cycles, the applique in Comparative Example A hadbecome yellowish gray with a Delta E of 8.6, whereas after 20 launderingcycles the applique in Example 2 was blue gray, substantially retainingits initial appearance with a Delta E of 3.6.

It is believed that a smaller Delta E can be attributed to 2 mechanisms:(1) higer brightness retention (less degradation of the reflector layerof the applique) and (2) an enhanced camouflaging effect of the colorant(greater absorption of light). In this case, after 20 and 15 launderingcycles, respectively, the applique of Example 2 had a slightly higherbrightness retention than the applique of Comparative Example A.However, it is further believed that the second mechanism discussedabove has a much more significant effect on Delta E than the firstmechanism.

EXAMPLE 3 AND COMPARATIVE EXAMPLES B AND C

In Example 3, an array of retroreflective elements on a temporarycarrier was prepared as in Example 1.

A binder composition comprising:

    ______________________________________                                        Amount      Component                                                         ______________________________________                                        100         Binder Material - 32.5 weight percent                                         solution in methyl isobutyl ketone of                                         thermosetting phenolic resin                                                  (formaldehyde phenol condensate),                                             nitrile rubber, and plasticizer (dioctyl                                      phthalate) in 5:3.3:1 weight ratio;                               1.8         Coupling Agent - A-189;                                           0.042       Dye - ZAPON ™ Black X-50;                                      ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about250 microns (10 mils) and dried at 66° C. (150° F.) for 10 minutes andthen at 93° C. (200° F.) for 5 minutes to yield the binder layer.

An adhesive like that used in Example 2 was coated over the binder layerto a wet thickness of about 250 microns (10 mils).

The applique was then wet laminated to a fabric as in Example 1. Thetemporary carrier was then stripped from the front of the applique toreveal the silver colored retroreflective surface.

In Comparative Example B, a retroreflective applique was made andapplied to a fabric in a similar manner as in Example 3 except the dyewas replaced with about 0.5 parts carbon black and about 2.0 partstitanium dioxide pigment provided in the binder layer. In ComparativeExample C, a retroreflective applique was made and applied to a fabricin a similar manner as in Example 3 except no colorant and no couplingagent were used. In both Comparative Examples B and C, similar butdifferent adhesives and fabrics were used. It is believed that the useof different adhesives and fabrics had at most a minimal effect on theretained brightness and color of the tested appliques.

The appliques were evaluated by washing for 25 cycles at a watertemperature of about 66° C. (150° F.) using FACTOR™ and ULTRASIL™cleaners. The laundering results obtained are shown in Table II.

                  TABLE II                                                        ______________________________________                                        Sample   Brightness.sup.1                                                                        Color Shift.sup.2                                                                           Color                                        ______________________________________                                        3        29         9.5          Bluish-gray                                  B         2        12.5          Greenish                                     C        <2        33.8          Yellowish/                                                                    Brownish                                     ______________________________________                                         .sup.1 Percentage of its initial brightness retained after 25 washings.       .sup.2 Delta E between sample after 0 and 25 washings.                   

EXAMPLE 4 AND COMPARATIVE EXAMPLE D

In Example 4, an array of retroreflective elements on a temporarycarrier was prepared as in Example 1.

A binder composition comprising:

    ______________________________________                                        Amount    Component                                                           ______________________________________                                        100       Binder Material - 50 weight percent solids                                    solution in methyl ethyl ketone/toluene                                       mixture (1:1 weight ratio) of VITEL ™                                      VPE-5545, a linear saturated polyester from                                   Goodyear;                                                           2.4       Binder Material - MONDUR ™ CB-75;                                0.15      Catalyst - dibutyl tin dilaurate;                                   0.05      Dye - 10 weight percent solution in methyl                                    isobutyl ketone of ZAPON ™ X-51; and                             1.5       Coupling Agent - Silane Z-6040, a gamma-                                      glycidoxypropyltrimethoxysilane from Dow                                      Corning Corp.;                                                      ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about200 microns (8 mils). The construction was then dried by passing on aconveyer through a series of four ovens with the following temperaturesand residence times: 66° C. (150° F.) for 1.5 minutes, 77° C. (170° F.)for 1.5 minutes, 77° C. (170° F.) for 1.5 minutes, and then 93° C. (200°F.) for 3 minutes, to yield the binder layer.

An additional layer of the same composition was coated over the binderlayer to a wet thickness of about 250 microns (10 mils). This additionallayer served as the adhesive layer.

The applique was then wet laminated to a fabric as in Example 2, exceptthe applique was dried on the fabric at 66° C. (150° F.) for 3 minutesand then at 93° C. (200° F.) for 3 minutes. The temporary carrier wasthen stripped from the front of the applique to reveal the silvercolored retroreflective surface.

In Comparative Example D, a retroreflective applique was made with abinder layer of the same composition as in Example 4 except the dye wasomitted. The binder layer was applied with a single coating of 175microns (7 mils) wet thickness and dried and cured at 66° C. (150° F.)for 2 minutes and 93° C. (200° F.) for 5 minutes to yield the binderlayer.

An additional layer of the same composition was coated over the binderlayer to a wet thickness of about 175 microns (7 mils) for the purposeof serving as the adhesive layer.

The resultant applique was then wet laminated to a polyester fabric(S-551-060, 3.11 ounce/yard² from Milliken and Co.) and the constructiondried and cured at 66° C. (150° F.) for 2 minutes and 93° C. (200° F.)for 5 minutes. The temporary carrier was then removed to reveal thesilver colored retroreflective surface.

The appliques were then evaluated by washing for the indicated number ofcycles at a water temperature of about 74° C. (165° F.) using FACTOR™and ULTRASIL™ detergents. The retroreflective brightness resultsobtained are shown in Table III.

                  TABLE III                                                       ______________________________________                                        Brightness.sup.2                                                              Cycles.sup.1   Ex. 4  Comp. Ex. D                                             ______________________________________                                         0             100    100                                                      5             74     60                                                      10             52     32                                                      15             28     25                                                      20             18     22                                                      ______________________________________                                         .sup.1 Number of wash cycles completed.                                       .sup.2 Percentage of its initial brightness that indicated sample retaine     after indicated number of wash cycles.                                   

The initial brightness of the applique in Example 4 was 658 candela persquare meter per lux and that of the applique in Comparative Example Dwas 578 candela per square meter per lux. After 20 laundering cycles,the applique in Example 4 was dark grayish silver in color, havingundergone a Delta E of 17.7 and the applique in Comparative Example Dwas grayish white, having undergone a Delta E of 31.7. Thus, even thoughthe retained brightness of the applique of Example 4 was lower after 20cycles, the camouflaging effect of its dye was great enough to result ina much smaller Delta E.

EXAMPLE 5

An array of retroreflective elements on a temporary carrier was preparedas in Example 1.

A binder composition comprising:

    ______________________________________                                        Amount    Component                                                           ______________________________________                                        350       Binder Material - 50 weight percent                                           solids solution in methyl ethyl                                               ketone/toluene mixture (1:1 weight ratio)                                     of VITEL ™ VPE-5545;                                             8.4       Binder Material - MONDUR ™ CB-75;                                0.53      Catalyst - dibutyl tin dilaurate;                                   0.18      Dye - 10 weight percent solution in                                           methyl isobutyl ketone of ZAPON ™ X-51;                                    and                                                                 5.4       Coupling Agent - Silane Z-6040;                                     ______________________________________                                    

was coated over the retroreflective elements to a wet thickness of about175 microns (7 mils). The construction was then dried by passing on aconveyer through a series of four ovens with the following temperaturesand residence times: 66° C. (150° F.) for 1 minute, 77° C. (170° F.) for1 minutes, 88° C. (190° F.) for 1 minute, and then 93° C. (200° F.) for4 minutes to yield the binder layer.

An additional layer of the same composition with the dye and couplingagent omitted was coated over the binder layer to a wet thickness ofabout 175 microns (7 mils) for the purpose of serving as an adhesivelayer. The applique was then wet laminated to an S-551-060 polyesterfabric and the construction dried and cured on a conveyer through ovensat 66° C. (150° F.) for 1 minute, 82° C. (180° F.) for 1 minute, and 93°C. (200° F.) for 5 minutes. The temporary carrier was then stripped fromthe front of the applique to reveal the silver colored retroreflectivesurface.

After conditioning the sample by maintaining it at a temperature of 66°C. (150° F.) for 7 days, the applique was evaluated by washing for theindicated number of cycles at a water temperature of about 78° C. (173°F.) using FACTOR™ and ULTRASIL™ cleaners. The applique had an initialretroreflective brightness of about 605 candela per square meter per luxand a retained retroreflective brightness as shown in Table IV.

                  TABLE IV                                                        ______________________________________                                        Cycles.sup.1 Brightness.sup.2                                                 ______________________________________                                         0           100                                                              10           80                                                               20           59                                                               30           48                                                               40           40                                                               50           38                                                               ______________________________________                                         .sup.1 Number of wash cycles completed.                                       .sup.2 Percentage of its initial brightness that sample retained after        indicated number of wash cycles.                                         

After 50 laundering cycles, the applique was grayish silver in color,exhibiting a Delta E of less than about 5.

EXAMPLE 6 AND COMPARATIVE EXAMPLE E

In Example 6, a silver colored retroreflective applique was prepared asin Example 5, except the oven temperatures and residence times were asfollows: 71° C. (160° F.) for 1 minute, 82° C. (180° F.) for 1 minute,88° C. (190° F.) for 1 minute, and then 110° C. (230° F.) for 4 minutes.

In Comparative Example E, a retroreflective applique was prepared as inExample 6, except the dye in the binder composition was replaced with1.5 parts SILBERLINE STAMFORD™ NGH Aluminum Paste, a non-leafing, 62 to74 weight percent solids in aromatic solvent aluminum paste fromSilberline Manufacturing Co., Inc.

The initial retroreflective brightnesses of the appliques were 605 and593 candela per square meter per lux, respectively. The appliques werethen evaluated for corrosion of the aluminum specular reflective layerby immersing in a 1 weight percent solution of HAMIX™ Detergent, a highpH detergent from Leverindus Nykoping, Sweden, in deionized water at 82°C. (180° F.) for the indicated time. The results obtained are shown inTable V below.

                  TABLE V                                                         ______________________________________                                        Example  Time.sup.1  Brightness.sup.2                                                                        Color Shift.sup.3                              ______________________________________                                        6        0           100       0                                                       2            42       2.7                                                     7           <2        5.0                                                     17          <2        9.8                                            E        0           100       0                                                       2            11       8.6                                                     7           <2        20.5                                                    17          <2        35.7                                           ______________________________________                                         .sup.1 Immersion time in hours.                                               .sup.2 Percentage of original brightness that sample retained after           indicated time of immersion.                                                  .sup.3 Delta E between sample's original appearance and appearance after      indicated time of immersion.                                             

It is believed that the above immersion test nearly completely destroyedthe reflector layer and the aluminum paste of the applique ofComparative Example E. This is believed to explain the large Delta E ofComparative Example E.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention.

What is claimed is:
 1. A retroreflective applique comprising a monolayerof retroreflective elements partially embedded in and protruding fromthe front surface of a binder layer and an adhesive layer on the rearsurface of said binder layer, said adhesive layer comprising betweenabout 0.01 and about 2.0 weight percent of a black chromium-azo dye tocamouflage the color of any exposed portions of said binder layer, saidadhesive layer being adapted for use in securing said applique to alaunderable substrate.
 2. The applique of claim 1 wherein said adhesivelayer comprises between about 0.1 and about 0.5 weight percent of saiddye.
 3. The applique of claim 1 wherein said adhesive layer comprises ahot melt adhesive.
 4. The applique of claim 1 wherein said dye has amolecular weight above about 300.